The applicant is aware of several prior art references dealing with membranous coverings, especially those dedicated to roof coverings.
For example, U.S. Pat. No. 1,774,858, issued Sept. 2, 1930 to R. Vorbau deals with a thermoplastic to thermoplastic bonding to provide a continuous covering. The bonding is done by using a repair ribbon which melts into the abutted seams of the adjoining thermoplastic segments. This method does not deal with laminated thermoset or thermoplastic layers, but deals with the gluing of layers of fabric together using a bonding resin, wherein the bonding resin impregnates the fabric and creates a physical hold.
U.S. Pat. No. 2,367,725, issued Jan. 23, 1945 to G. Lindh et al is a method for joining thermoplastic materials using hot air melting of thermoplastics including using a meltable mass of like material as the "extra glue". It should be noted that these materials are not weatherable, and there is no teaching in that reference as to how one would make such materials weatherable. Further, the Lindh et al method does not deal with laminates of dissimilar materials, and the problems associated with bonding therein. This reference discloses the top cap method and the overlap method of seaming single ply materials.
An additional reference showing welded polymeric articles is U.S. Pat. No. 3,927,233, issued to Robert J. Naidoff on Dec. 16, 1975 which discloses butt-welded polymeric articles. It deals with bonding like substrates to like substrates. It does not deal with bonding unlike substrates to each other, nor does it deal with laminated structures at all. The essence of the invention is the use of a curable polymeric plug which can be inserted between the various segments of the polymeric sheets and then compressed, heated and cured to bind the polymeric sheets together.
In U.S. Pat. No. 4,563,379, issued Jan. 7, 1986 to Gerhard Kruger, there is disclosed the use of a reinforcing organic resin mixed intimately with the thermoset resin which causes the thermoset to bind together upon heating, by forming an interpenetrating network non-crosslinked thermoset which does not depend on a chemical cure.
Finally, there is U.S. Pat. No. 3,071,503, issued Jan, 1, 1963 to J. R. N. Dubois, which is included herein as a reference showing the many types of seams and bonds that are needed to form membranous coverings, but of course, not with the materials and methods of the instant invention.
Thus, it appears that the instant invention has not been disclosed in the prior art and the advantages of the instant invention are not suggested by the prior art and are therefore not obvious to those skilled in the art.